The present invention relates to a fluid distribution device. Such a device is suitable for providing a debris resistant fluid flow path within a cooling system.
Electrical machines, such as generators and motors, are becoming ever more compact. Furthermore, the currents being handled within such machines are generally increasing. Electrical generators frequently include rectifiers. The rectifiers are often provided as part of the rotor assembly and are mounted adjacent the rotor coils. There is little space within the generator assembly to provide heat sinks, and therefore it is necessary to pass a cooling fluid over the rectifiers in order to remove heat from them. It is important that heat is removed from the rectifiers as excessive heating will result in shortening of their working life span or possibly component failure.
It is known, within the context of a generator system, to mount rectifiers on a carriage which is attached to and rotates with the rotor shaft of the generator. The rotor shaft has a through bore through which cooling oil is pumped. A drilling is provided in the rotor shaft adjacent each rectifier such that oil can escape from the rotor shaft and spray onto the rectifier. There is, of course, a balance to be struck between the size of the drilling and the oil pump providing the flow of cooling oil. In most space constrained systems the maximum flow rate of a pump providing the cooling oil flow is constrained. The flow of cooling oil may have to be divided amongst many components and consequently it becomes desirable to keep the oil flow to any one component at a small a rate as is consistent with proper functioning of that component. This, in general, means that the drillings in the shaft are of a limited diameter. If the diameter of the drilling is too large, this results in preferential flow of oil through the large diameter drilling at the expense of oil flow to other components. However, with small diameter drillings there is a risk that debris in the oil could cause the drilling to become blocked thereby impeding the flow of cooling oil to the component.
According to the present invention, there is provided a fluid distribution device, comprising an inlet having a first width, an outlet having a second width less than the first width, and a separator, wherein the separator receives fluid from the inlet and directs solid matter along a first path and substantially debris free fluid towards the outlet, and wherein at least one aperture having a third width which is less than the second width is provided intermediate the separator and the outlet.
It is thus possible to provide a distribution device which is resistant to blocking by debris.
Advantageously the inlet is dimensioned such that it is large in comparison to the expected size of debris within the fluid, and consequently is difficult to block. Debris passing through the inlet is directed towards the separator where, because of density differences between the debris and the fluid, the debris is separated from the fluid.
Advantageously the distribution device is mounted for rotation with a shaft, with the shaft passing through a substantially central bore of the distribution device. Preferably the separator comprises a first chamber of a first depth measured with respect to the central bore of the distribution device. A fluid flow path to the outlet is provided from the first chamber at a position away from the radially outer most wall thereof. Thus, as the separator rotates with the shaft, debris is forced under the action of centrifugal forces towards the radially outer most wall where it becomes held. Fluid substantially free of debris can then flow towards the outlet.
Preferably the first chamber is in fluid flow communication with a second chamber. The chambers may join at a step like interface. The interface between the first and second chambers is advantageously partially bounded by the rotor shaft in order to form an interface aperture of the third width. The interface aperture may be in the form of an elongate slot which can serve to trap debris which has not been centrifuged out of the fluid. The elongate nature of the slot means that any single piece of debris which gets trapped at the slot only blocks a relatively small portion of the slot whilst leaving the remainder of the slot open to fluid flow. The second chamber then leads to an outlet duct which directs oil towards a component to be cooled. The width of the outlet duct is greater than the width of the slot, thereby ensuring that any debris which passes through the slot will also pass through the outlet.